The process of changing the color of hair, can involve depositing an artificial color onto the hair which provides a different shade or color to the hair, and/or lifting the color of the hair, such as lightening the color of dark hair to lighter shades.
Imparting a color change or color effect on hair can be done using permanent, demi-permanent, and semi-permanent or temporary hair coloring products. Conventional permanent hair coloring products are dye compositions comprising oxidation dye precursors, which are also known as primary intermediates or couplers. These oxidation dye precursors are colorless or weakly colored compounds which, when combined with oxidizing products, give rise to colored complexes by a process of oxidative condensation. The oxidizing products (i.e., developers) conventionally use peroxides such as hydrogen peroxide as oxidizing agents. Such permanent hair color products also contain ammonia or other alkalizing agents such as monoethanolamine (MEA) which causes the hair shaft to swell, thus allowing the small oxidative dye molecules to penetrate the cuticle and cortex before the oxidation condensation process is completed. The resulting larger-sized colored complexes from the oxidative reaction are then trapped inside the hair fiber, thereby permanently altering the color of the hair. Demi-permanent dyeing also utilizes oxidation dye precursors, but are often used with a low volume developer (e.g., 2-3% hydrogen peroxide), as well as MEA. Semi-permanent dyeing uses direct dyes, which are nonionic or ionic dyes and colored compounds capable of producing a more or less pronounced change of the natural color of the hair, resistant to shampoo-washing several times. These dyes may or may not be used in the presence of an oxidizing agent. In contrast with oxidation dye precursors, a direct dye is a relatively voluminous molecule that does not penetrate easily into the core of the fiber.
Permanent hair color has the obvious advantage of the most durable of the hair color treatments described above. However, some of these active ingredients can be harsh and cause adverse reactions in users. Thus, there is a desire to provide hair color compositions which have the added benefits of better conditioning, scalp comfort, and the need for less dyes.